In order to assess the utility of various test systems, different aspects of their potential should be explored. If one type of genetic damage is more easily detected within a system, this might be the criterion of choice. Using the Mouse Lymphoma cell line L5178Y, mutations at the TK locus were induced by chemical treatment. Studies utilizing the same mutagens are conducted on the frequencies of induction of chromosomal damage and aberrations, and compared with the point mutation frequency.